172 GARDEN DESIGN 



ally built terraces water must be introduced in 

 prepared basins. 



To merely run in water is seldom sufficient to 

 obtain a pond, and even on the strongest clay 

 the surface soil is porous. For gravel and sandy 

 soils a concrete bottom is recommended, for clay 

 may be difficult to procure, and gravel forms the 

 bulk of concrete. The place should be excavated 

 at least i ft. below the depth of water required, 

 and 18 in. wider, and the soil carefully put aside 

 for raising plantations and promontories. The 

 bottom and sides must be rammed as firm as 

 possible. The concrete should be composed of 

 six parts pit ballast and clean sand to one of 

 Portland cement. The bottom receives a layer of 

 i ft., and the sides one of 18 in. When set, three- 

 quarters to an inch of pure cement is floated over 

 the rough concrete, trowelling it well into every 

 hollow, and leaving a perfectly smooth surface. 



Where clay is available puddling is effective 

 and much cheaper. The clay must be free from 

 stones and worked up with water until it is plastic, 

 and then plastered and rammed on the bottom 

 and sides to the same thickness recommended for 

 concrete. It is very messy work, and must be 

 thoroughly done or a few cracks may spoil the 

 whole. It must not be allowed to dry while 

 waiting for the water to come in, and mats or 

 other coverings should be laid over the portions 

 done, until all is finished. 



